Abaixo está uma instrução que descreve uma tarefa de geração de SQL, combinada com uma entrada que fornece mais contexto sobre os esquemas de tabela disponíveis. Escreva o código SQL que responda adequadamente à solicitação
 ###Instrução: Qual é o número de constituintes do distrito de Seoni e nenhum deles está reservado?
 ###Tabelas: CREATE TABLE cantonal_school_systems (cantonal_school_systems_id AUTO_INCREMENT PRIMARY KEY, Canton VARCHAR, Years of Kindergarten INT, Years of Kindergarten provided VARCHAR, Years of Kindergarten legally required VARCHAR, Length of Primary School INT, Length of mandatory Secondary School INT, Separate Secondary Schools? VARCHAR, Cooperative Secondary Schools? VARCHAR, Integrated Secondary Schools? VARCHAR) CREATE TABLE franchises (franchises_id AUTO_INCREMENT PRIMARY KEY, Team VARCHAR, Province VARCHAR, Owner(s) VARCHAR, Price VARCHAR, Captain VARCHAR, Head coach VARCHAR, Icon Player VARCHAR) CREATE TABLE assembly_segments (assembly_segments_id AUTO_INCREMENT PRIMARY KEY, Constituency number VARCHAR, Name VARCHAR, Reserved for ( SC / ST /None) VARCHAR, District VARCHAR, Number of electorates (2009) INT) CREATE TABLE academic_staff (academic_staff_id AUTO_INCREMENT PRIMARY KEY, Lecturers INT, Associate professors INT, Assistant professors INT, Professors INT, Total INT) CREATE TABLE top_ten_serial_dramas_in_ratings (top_ten_serial_dramas_in_ratings_id AUTO_INCREMENT PRIMARY KEY, Rank INT, English title VARCHAR, Chinese title VARCHAR, Average INT, Peak INT, Premiere INT, Finale INT, HK viewers VARCHAR)  
SELECT Constituency number FROM assembly_segments WHERE Reserved for ( SC / ST /None) = none AND District = seoni